This is a Phase I study of cancer chemotherapy of all-trans-retinoic acid (ATRA) metabolism in hormone-refractory prostate cancer. ATRA is known to induce its own metabolism, but the drug metabolizing enzymes responsible for this are not well characterized. The phenomenon of auto- induction will be investigated in a 3 phase study using the 'Pittsburgh' cocktail to also evaluate selected drug metabolizing enzyme activity in patients with prostate cancer. Drug metabolizing enzyme phenotyping (chlorzoxazone, debrisoquine, caffeine, mephenytoin, and dapsone) will be done simultaneously with ATRA pharmacokinetics on Day 1 and 14 of a daily dose of ATRA and again after a two week wash out from ATRA therapy. This study will also evaluate safety and efficacy of ATRA therapy.